Spread spectrum communications may be based on, for example, Time Division Multiple Access (TMDA), Code Division Multiple Access (CDMA), and Frequency Division Multiple Access (FDMA). FIG. 1 is a diagram illustrating a data/voice Time Division Multiple Access (TDMA) communication structure 100, according to the prior art. TDMA, which is packet-based, assigns each call a certain portion of time on a designated frequency. FIG. 2 is a diagram illustrating a TDMA packet structure 200, according to the prior art.
Conventionally, the decoding of received signals in TDMA has involved correlating the received signals as they are being received. The decoding occurs in a serial fashion in the time domain. However, the start of a received packet has been very difficult to reliably determine. Accordingly, misdetection of the start of a received packet occurs with some frequency. This is particularly true in very low signal-to-noise (SNR) conditions and under various adverse signal impairments.
Accordingly, it would be desirable and highly advantageous to have an improved method and apparatus for correlation detection in spread spectrum signals. Such a method and apparatus should preferably be capable of accurately detecting the start of a received packet. Further, such a method and apparatus should preferably be able to accurately operate in very low SNR conditions and under various adverse signal impairments.